Tattooing is an ancient art, dating back as early as 12,000 BC (Grumet, Am. J. Orthopsychiatry, 53:482-492 (1983)), when ash was rubbed into skin incisions. Puncture tattooing later became popular and is practiced even today. Modern tattoo inks cover a wide pallet of colors and use different tattoo “inks.” Today, about 1 in 5 young adults in the United States have been injected with these substances, by people with little or no medical training.
The desire to remove tattoos is probably as old as their existence. The fraction of tattooed people who will seek tattoo removal is unknown, but substantial. The earliest report of tattoo removal was by Aetius, a Greek physician who described salabrasion in 543 AD (Scutt, Br. J. Plast. Surg., 25(2):189-194 (1972)). Grossly destructive methods such as dermabrasion and argon or CO2 laser vaporization are still used (Apfelberg et al., Br. J. Plast. Surg., 32:141-144 (1979); Apfelberg et al., Ann. Plast. Surg., 14:6-15 (1985); Bailin et al., J. Derm. Surg. Oncol., 6(12):997-1001 (1980); Reid and Muller, Plast. Recons. Surg., 65(6):717-728 (1980)), but they have a high risk of scarring. Leon Goldman first reported laser tattoo removal in 1965 and then in 1967 using a Q-switched ruby laser (Goldman et al., J. Invest. Dermatol., 44:69-71 (1965)); Goldman et al., JAMA, 201(11):841-844 (1967)). Later cases reported by Reid et al. (Br. J. Plast. Surg., 36:455-459 (1983)) revealed good results with a Q-switched ruby laser, particularly when used on black and amateur tattoos. These results were further refined based on concepts of selective photothermolysis (Anderson and Parish, Science, 220:524-527 (1983)).
Because of the variety of tattoo ink colors, a variety of laser wavelengths are necessary to remove colored tattoos. High-energy Q-switched ruby (694 nm), alexandrite (755 nm), Nd:YAG (1064 nm) and frequency-doubled Nd:YAG (532 nm), lasers are now used, which emit visible and near-infrared light pulses ranging from about 10-100 ns duration (Levins et al., Lasers Surg. Med. Suppl., 3:63 (1991); Kilmer and Anderson, Dermatol. Surg. Oncol., 19:330-338 (1993); Kilmer et al., Arch. Dermatol., 129:971-978 (1993); Fitzpatrick and Goldman, Arch. Dermatol., 130(12):1508-1514 (1994)).
Before laser treatment, tattoo ink particles are typically found within dermal fibroblasts and mast cells, predominantly in a perivascular location (Mann and Klingmuller, Arch. Dermatol. Res., 271:367-372 (1981)). The mechanism by which Q-switched lasers remove tattoos involves selective rupture of these cells, breakdown of tattoo ink particles, and ink removal by transepidermal elimination and/or lymphatic transport (Taylor et al., J. Invest. Dermatol., 97:131-136 (1991); Ferguson et al., Br. J. Dermatol., 137:405-410 (1997)). The risk of scarring after Q-switched laser treatment is substantially lower than after excision, dermabrasion, or CO2 laser vaporization. However, much of the ink remains inside the body, either in regional lymph nodes or as a lightened, residual tattoo in the skin. The number of Q-switched laser treatments required for complete tattoo “removal” depends on the type of tattoo ink, body location, and laser. Amateur tattoos made with carbon (ash, graphite, India ink) respond best, typically clearing in most patients after 4-6 treatments. Multicolored tattoos on the extremities tend to respond poorly. Typically, less than half of these tattoos can be cleared in less than ten treatments, regardless of the type of Q-switched lasers used.
Tattoo inks are probably the least-regulated substances routinely injected into people in our society. The purity, pharmacology, biodistribution, and identity of most inks are unknown. None are approved by the Food and Drug Administration (Anderson, N. Engl. J. Med., 326:207 (1992)). New bright-colored inks are being introduced at an unknown rate, and are often those most difficult to remove by laser treatment. Although most tattoos appear to be well tolerated, there are reports of infection, photosensitivity, and acute and chronic hypersensitivity reactions (Novy, Arch. Dermatol., 49:172-173 (1944); Bjornberg, Arch. Dermatol., 88:83-87 (1963); Loewenthal, Arch. Dermatol., 107:101-103 (1973); Goldstein, J. Dermatol. Surg. Oncol., 5:896-900 (1979)). Tattoo ink is permanently taken up in lymph nodes in addition to the intended target organ, skin. The long-term health risk of tattooing is unknown. The present situation may eventually lead to significant problems.
In view of the history, popularity, limited safety data and limited treatment options for tattoos, safe, removable tattoo inks are desirable.